If your LG Smart TV shows Invalid Format while plugging any external device like a gaming console, DVD player, or cable box, it means that your TV does not support the resolution of the output device. However, you can fix this error by changing the resolution of your LG smart TV or the specific external device.
Gaming consoles like PlayStation, Xbox, and Nintendo Switch won’t operate in the same resolution. When you connect your LG Smart TV to PlayStation using the HDMI cable, the resolution on your TV and the console will vary, displaying the Invalid Format error message. To fix the Invalid Format error, there are some quick solutions.
Fixes for Invalid Format Error on LG Smart TV
The first fix you want to try to get rid of Invalid Format is to change the resolution on your LG TV. To do so,
How to Change Resolution on LG Smart TV
 Press the Home button and open the Settings menu.
 Navigate to the Picture option and hit Enter.
 Choose the Aspect Ratio option.
 In the Aspect Ratio, there are six options available to change the format.
- 16:9 – This is the default resolution. With this, the TV adjusts the picture on the horizontal side to fill the screen.
- Just Scan – In the Just Scan option, the edges of the screen (top and bottom) are cropped by 1-2% of its value. This level of cropping is done to show the complete video. Modes like DTV, DVI-DTV, HDMI-PC, HDMI-DTV, and CADTV are cropped in Just Scan.
- Set By Program – This mode is preferred when you connect the cable box to LG TV. This mode will adjust the image size to match the TV program.
- 4:3 – This option is preferred in non-widescreen TV models. Most of the video content is set to 4:3. So, setting the aspect ratio to 4:3 will give you the original view. In this mode, you will get black bars on the left and right sides of the screen.
- Zoom – With this mode, you will get zoomed view of a picture or a video. Zoom mode will resize the image to fit the screen width. While zooming, the top and bottom portions of the image will be cropped.
- Cinema Zoom – Cinema Zoom is preferred when you connect external video sources. This mode changes the aspect ratio to the cinemascope ratio (2.35:1). With this effect, the image on your TV will be distorted. If you want, you can customize the zoom level from 1 to 16.
 For RGB-PC input, choose 4:3 or 16:9 aspect ratio. When using this input, there is no other option to adjust the aspect ratio.
How to Change Resolution on External Device
Changing the resolution on external devices is the least preferred one. Changing the external device’s resolution will affect the output on your TV. Try to match the resolution with your LG TV itself. If all the available resolution on your TV is resolving the Invalid Format error, you can change the external device’s aspect ratio. The steps to change the external device’s aspect ratio depends on the device you are using. In most cases, you can find these customization options in the Display Settings. For instance, on PlayStation consoles, go to Settings → Sound and screen → Video Output Settings → Choose the resolution.
To fix the overscan or underscan problem, press the Home button and navigate Settings >> Picture >> Aspect Ratio, and change the setting to 16:9 or Just Scan.
Choose Expert (Dark space, night) picture mode is one of the best picture settings on LG Smart TV.